Print 28 comment(s) - last by RW.. on Jun 3 at 5:48 PM

AACS loses the keys to its house, quickly changes locks

Efforts that began in December 2006 and continued through February 2007 lead to the discovery of the Processing Key used to encrypt high-definition media with the Advanced Access Content System. The work of a small hacking community created essentially a silver bullet that was able to defeat the copy protection of all HD DVD and Blu-ray Disc media on the market at that time.

The Advanced Access Content System Licensing Administration (AACS LA) acknowledged the effectiveness of the hack and began to enact measures to restore the integrity of its technology. Beginning May 22, which is most notably the release date of the Matrix trilogy on HD DVD, all high-definition titles shipped with Media Key Block (MKB) v3 – a new encryption key version that would render the previously discovered Processing Key obsolete.

Interestingly enough, the AACS’ updated protection measures appeared to be defeated by SlySoft, makers of AnyDVD HD software, before the new MKB versions officially hit streets. The AACS has yet to officially issue a statement and is current investigating the latest attack on the system, according to comments made by Richard E. Doherty, director of technology strategy at Microsoft, who is also actively involved with the AACS.

The initial method used by hackers to snoop the sensitive encryption keys from HD DVD and Blu-ray were accomplished using PC software. More specifically, hackers took advantage of holes in WinDVD to read data straight from the PC’s memory. While such a hack may not have been possible without the existence of software players, the AACS appears unshaken about high-def media on computers.

“Just to clarify, the original attack was on certain software players that proved to be vulnerable, and did not and does not represent a widespread break in the AACS ecosystem ... In the past PC's have typically been a big target for hacking activities, as they are designed to run arbitrary software programs. But the line between PCs and traditional CE devices is clearly blurring – and many of the best PVR systems (in my opinion) are highly customizable and capable of running user-designed software,” explained Doherty, also pointing to how a Windows Media Center box could be strong addition to home theatres.

“Keep in mind, however, that AACS is aware of the history and attack vectors of PC playback systems, and there are several technical measures (such as KCD and the entire proactive renewal system) that are designed specifically to address the particular issues of PC-based protection,” Doherty added.

The uncovering of the Processing Key to HD DVD and Blu-ray happened in February, leaving some to wonder why it wasn’t until months later until the appearance for a new MKB. Doherty provides the answer, “AACS of course has the technical means to revoke overnight. But the current license agreement generally provides for 90 days. This is to allow time for the manufacturer to repair the product and presumably fix the vulnerability, and time to rollout the patches to the affected users.”

The apparent grace period is done in the interest of consumers, as if the key were revoked immediately, legitimate consumers could find themselves with an unplayable disc until a software update. Despite the quick ‘rehack’ of the AACS, the system is designed to avoid another complete defeat like CSS – the technology used to protect DVD.

“You have seen a revocation cycle occur which has required upgrades to certain software players to make them more robust to known styles of attack. The AACS system was designed to deal with these sorts of attacks, and remains intact as a technology. This is in contrast to CSS, which is vulnerable to direct, brute-force attacks,” said Doherty, who then explains it in even simpler terms. “The analogy we sometimes give is: if you lock your house, but leave the keys lying on the street, then there's really nothing wrong with the locks or with the concept of locks in general. If you don't find the keys, you can change the locks if you like.”

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RE: Analogy
By Screwballl on 6/1/2007 11:03:02 AM , Rating: 3
and another bit of info...

Locks keep honest people honest
dishonest people will always find a way to the other side to get what they want whether its through the lock or through a window

RE: Analogy
By BMFPitt on 6/1/2007 11:18:27 AM , Rating: 2
In all reality, I think the encryption is the least important part of what prevents common users from pirating. Inconvenience is much more critical. All that is needed to keep 95% of would-be copiers from doing it is a do-not-copy bit enforced by the authoring software and OS. Tools would be as easy to get for going around that as they are for encrypted discs, but this way it gives a nice challenge and bragging rights to those who write it.

RE: Analogy
By Christopher1 on 6/1/2007 8:07:33 PM , Rating: 3
Problem is that the Supreme Court has said that people are ALLOWED to make 1:1 copies of CD's and DVD's as a form of investment protection.

RE: Analogy
By nilepez on 6/3/2007 12:56:47 PM , Rating: 2
Has DMCA made it to the SCOTUS? For some reason, I'd swear that they actually upheld the applicable portions. As a result, you have a right to copy it, so long as you don't hack your way past copy protection.

So yeah, we have the right to copy it, but if it's copy protected, you'll have to commit a felony to exercise that right....the DMCA is a totally f*cked up law.

RE: Analogy
By MonkeyPaw on 6/1/2007 3:05:48 PM , Rating: 3
Locks keep honest people honest
dishonest people will always find a way to the other side to get what they want whether its through the lock or through a window

By this logic, I suppose you can throw me into your "honest" category, as I've never broken into someone's personal property (home, car, or otherwise). The problem is, I don't go around checking to see if people are locking their doors, or even wondering if their doors are locked for that matter. There are people out there that don't think about stealing, at least in the case of breaking and entering. That's why there are entire towns where people don't ever lock their doors.

I think the comparison of AACS to home locks is a little flawed anyway. Finding a key to a home isn't really a prize. You don't steal a home (what they key protects), you steal what's in it. Besides, just getting into a house doesn't mean you're in the clear. Someone could be home, there could be a dog, they could have a security system, someone could see you. There are still other barriers.

A better comparison might be like finding a set of car keys. The key protects the car from unauthorized use. Once you have the key to the car, you can get in it, start it up, and drive it away like it's yours. It's not yours, but you have full access to its features until you get caught. To go a step further in this analogy, consider that there are auto makers that allow you to replace your lost keys based off a simple code, but it's specific to your vehicle only. AACS would be like General Motors having a key code hidden in every GM VIN that will tell you how to make a key that starts any GM car ever made. Once you figure out that code, you can produce the key and steal any GM car you like.

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